“Ultimately, smoke taint is the objectionable note in wines produced from smoke-exposed grapes. It is perceptible by smell, taste and aroma,” said Wesley Zandberg, an associate professor of chemistry and member of the Wine Research Centre at the University of British Columbia’s Okanagan Campus.

Smoke’s distinctive odour is created by specific phenolic compounds. Volatile phenols created by burning biomass are transported into ripening grapes by smoke, which is absorbed and then linked to the grape’s sugars. During fermentation, those sugar-bound, smoke-derived phenols are broken back down, releasing the original pungent phenols into the wine. “People in the industry might argue that we should maybe call it smoke impact,” Zandberg said. “This is because not all smoke-exposed grapes produce smoke-exposed wines. That’s important to note.”

There are also ways to mitigate its effects.

Reverse osmosis

For many years, reverse osmosis has been a common method for removing various taints from wines. It works by forcing the wine through a semi-permeable membrane, which removes larger molecules such as smoke-derived phenols. It has been used primarily by bigger wineries, which have the money and resources to make it work. “But by the time you’ve removed the offensive molecules, you’ve also removed much of the pleasant aromas of the wine too. It certainly hasn’t produced anything that’s worth the cost,” said Zandberg.

Jennifer Kelly, a senior scientist at Brock University’s Cool Climate Oenology and Viticulture Institute, shares a similar perspective. “Reverse osmosis is not necessarily targeted for these compounds and could potentially remove other compounds in the wine that may be favourable,” she said. A winemaker, she says, must then find other ways to add a wine’s positive characteristics back into the bottle through blending or other means.

Timing matters

A day of smoke likely isn’t a big deal, but lingering smoke and the resulting extended exposure of the fruit to the particles will likely be an issue. It’s also worth considering the time of year the smoke occurs. Spring isn’t as big of a deal as later in the season. “Grapes are most susceptible seven days post-veraison,” said Kelly. “That timing can make or break a vintage.” Before committing to fermenting the entire harvest, try a microferment, Kelly says. “The grapes may look clean and smell clean, but they may not be clean,” she said. “A trial microfermentation would be a really good idea.”

Pick fruit later and use oak

“It is important to note that many of the same phenols present in smoke are also found in oak,” Zandberg said. “Clearly, context and concentration are both important.”

Like Zandberg, Val Tait, winemaker and general manager of Gold Hill Winery in B.C.’s Okanagan Valley, prefers not to call it smoke taint. Instead, she uses the term smoke influence. “For me, what has worked is to bring it into the cellar and try to develop a wine where that profile fits. That means making a wine that’s bolder, more expressive,” she said.

“The fruit is picked later, when it has much more ripe black fruit flavours, and [is] then brought into the cellar to work with oak with a higher toast. More extended maceration, too, [helps] to build the wine up so that it’s a bolder expression and the smoke segues into that quite nicely.” If you fight against the smoke and try to make the style you made in previous vintages, you’ll fail, says Tait. “You’ll make a very disjointed wine. Just find a way to work with it,” she said.

Kelly says that sometimes, oak chips can be effective for masking smoke. “But well-toasted barrels can have a compounding effect if you have a smoke-tainted wine,” she said.

Consider carbon

Libby Nixon, assistant winemaker and assistant viticulturist at Noble Ridge, has found that adding carbon to the wines (post-ferment for reds and at the juice stage for whites, rosés and hard pressings) can help somewhat. “The smoke will bind to the carbon and then you can just take it out,” Nixon said. “It’s cost-effective, but you don’t want to add too much because it will strip away some of the desirable characteristics.”

Hand harvest

Picking grapes by hand helps limit the number of leaves and extraneous material before fermentation; the leaves may make the perception of taint worse, Kelly says.

Limit skin contact

From Zandberg’s perspective, research needs to focus on the way grapes and smoke interact. He says these targeted strategies and in-winery reduction are particularly exciting. “Chemically understanding the interaction between smoke and the surface of a grape is critical. If we can understand this at a molecular level, we can manipulate it at a molecular level,” said Zandberg. “Then we can concentrate on how we can mitigate it in the winery.”

Grapes are most susceptible seven days post-veraison. That timing can make or break a vintage.

Jennifer Kelly, Brock University

Limiting the grapes’ skin contact during fermentation – as in, no hard pressings – may prevent some taint.  That’s because “skin thickness and bunch compactness can also have an impact,” says Kelly. It’s worth noting that some grapes seem to be more susceptible to smoke exposure than others. Syrah and Shiraz, for instance, naturally contain these compounds. If possible, blend wine from a previous vintage or a smoke-free vineyard to dilute the effect of the taint.

Pick yeasts carefully

Zandberg keeps an empty wine bottle on his desk, from an especially smoky vintage. The winemaker used “fancy yeasts,” Zandberg says, the sort associated with pleasant aromas. That particular bottle was marketable, but vintages from the same varietals of grapes produced by a nearby winery had to be pulled from the shelves. “Yeasts can make a big difference to smoke influence if we have a better understanding of how yeast-produced aromas can make, or in some cases, enhance, the smokiness,” said Zandberg. In other words, when potential smoke taint is a concern at harvest and commercial yeasts are being used, it’s important to select yeast strains carefully. “You should find strains of yeast that are less prone to smoke taint,” Zandberg said.

Kelly said, “They can enhance fruity aromas and esters to mask the smoke.” Kelly also says that grapes grown 50 to 80 kilometres from the fire typically see the most smoke influence. “Distance is important,” she said. “Beyond that, it doesn’t seem to be as impactful.”

Stay on top of the research

Mitigation research is underway now in Canada, Australia and the U.S., and results are released periodically. Past studies include washing the vines and grapes with water, ethanol and milk; none have changed the perception of smoke in the finished wines. In 2019, a group of researchers at the University of Adelaide in Australia applied kaolin (clay) to fruit approximately 10 days after the start of veraison, but before smoke exposure. Results showed its effectiveness depended on the extent of coverage; Merlot seemed to benefit from the kaolin spray, but Sauvignon and Chardonnay didn’t show much difference because the kaolin didn’t adequately adhere to the fruit.

Also at the University of Adelaide, researchers have had some success experimenting with molecularly imprinted polymers, adsorbents designed to bind smoke taint compounds, removing them from wine. “We’re also working with activated carbon fabric to prevent smoke contamination of grapes in the vineyard – again, results are promising, but there are some logistical challenges to overcome,” said Kerry Wilkinson, a professor of oenology at the University of Adelaide. “Results from trials combining separation technologies such as membrane filtration and spinning cone column distillation with the use of adsorbents are also promising.”

Look ahead to next year

The thing about smoke influence is that it’s hard to predict how or when it will show up. Sometimes, it’s evident at crush, when making the wine. Other times, it may not show up in the juice, but will show up months or even years down the road, long after the wine has been bottled. “It’s a bit tricky,” Kelly said. “These phenols can be odourless in the juice and emerge later, once you’re drinking the wine.”

Conversely, sometimes the influence shows up scientifically, but isn’t noticeable to the drinker. Some of Zandberg’s research is about “trying to deduce when smoke exposure will result in taint and when it will not,” he said. “Just because I can measure it chemically doesn’t mean the wine is bad. It just means I have really sensitive instruments.”

If experiencing a bad year, look ahead to the next. Smoke doesn’t seem to leave a lasting effect on vineyards. If a vineyard experiences smoke one year, but nothing the following year, that following year will likely be free of taint. “It won’t be a forever problem,” Kelly said. “I think it’s valuable for people to understand that.”

What is clear is that wildfires aren’t going away. “Climate change is making … our summers drier and that is leading to an increase in fires,” said Kelly. “But we are increasing the knowledge that helps winemakers better understand the risks and how to mitigate the effects [of smoke taint] down the road.”

Despite its global reach, Lallemand is a Canadian company. Since 1952, it has been owned and operated by the Chagnon family and it is headed by Antoine Chagnon, part of the third generation of the family to be involved. However, the company’s roots go back much further to an Alsatian immigrant in the 19th century who started a baking yeast business in Montreal, Que.

The Chagnon family, company headquarters and research facilities, and most of the team’s Canadian employees are still located in Montreal, but there are also production facilities and offices in Ontario. Yeast plants are located in 14 countries, including Austria, Canada, Germany, Portugal and Italy. These days, in addition to baking yeasts, Lallemand has products for brewers, distillers and, of course, winemakers.

While there’s much talk about spontaneous (wild) yeasts in winemaking circles these days, it may not be the correct choice for many wineries as the risks involved – stuck fermentation, unpredictable results, etc. – can be expensive, time-consuming and unpalatable. That’s why commercial yeast is essential as the guesswork has been removed, which allows winemakers to focus on other aspects of their wine.

“We don’t really create yeasts,” said Gordon Specht, Lallemand’s area manager, North America. “We simply select the best from nature.”

It takes about four years, and sometimes as long as seven, to select and develop a commercial yeast product. A Lallemand or university researcher will take samples at a winery or processing facility, and then set up test fermentations to see if the yeast shows potential, asking the following questions: Does it ferment well? Does it ferment quickly? Is it strong and active? How does the resulting wine taste?

We don’t really create yeasts. We simply select the best from nature.

Gordon Specht, Lallemand

“Sometimes we’ll find one that seems to check all the boxes: It’s a reliable fermenter. It doesn’t produce any funky or off aromas or flavours,” Specht said. “Then we see if we are able to dry it and offer it in a commercial format.”

Most wineries buy yeasts in an active dried form. “It has less than eight per cent moisture content, so it’s quite stable,” Specht said. “And it can be stored at the winery for a long time.” A typical yeast is shelf-stable for up to four years. “After that, they lose their robustness,” he said. “It takes them longer to wake up.”

Lallemand Oenology offers about 100 wine yeasts, all geared toward specific grapes, fermentation conditions and winemaking styles. Winemakers can request charts to help choose the yeasts and specific yeast derivatives they need to express the flavour profiles they want in their wines.

The Lallemand Oenology team, which includes top microbiologists, food engineers and oenologists from around the world, works with oenology schools and research centres to develop new products. They collaborate with the University of British Columbia Wine Research Centre, Niagara College’s Winery and Viticulture Technician Program and Brock University’s Oenology and Viticulture Program, testing on small batches of yeasts. International collaborations are also key to Lallemand’s business.

Lalvin New Burgundy Chardonnay is a vigorous new yeast strain that was isolated from Chardonnay fermented in France by the Centre Oenologique de Bourgogne. Lallemand’s researchers selected it because it is a reliable fermenter and it has the ability to contribute to a fresh, refined Chablis style with mineral, citrus and floral notes.

“It’s very good at complimenting styles that are more flinty and mineral, more of a classic Chablis style,” said Specht. “This is for that lean, crisp, fresh mineral style of Chardonnay, not that fatty, oaky, creamy style.”

Another new Lallemand product is the Level 2 Initia Metschnikowia Pulcherrima, a non-Saccharomyces yeast selection that helps protect white and rosé juice from oxidation during the winemaking process. From a selection made by Vincent Gerbaux at the Institut Francais de la Vigne et du Vin in Beaune, France, it results in fresher aromatics and brighter colours for white and rosé wines.

Saccharomyces is the typical food yeast used in baking, distilling and winemaking, and has been a primary part of the Lallemand Oenology catalogue since the get-go. However, these days the team has also been putting a lot of research emphasis on non-Saccharomyces yeasts, exploring their potential in the winemaking process. Lallemand offers five different types in North America, and they can already see where these products are proving to be useful for winemakers, Specht says.

Our basic philosophy is to find unique products to help winemakers. We are always looking toward the future.

Gordon Specht, Lallemand

One appeal is their protective capabilities, which help to keep freshness and slow oxidation. “Normally, the only way you can achieve this protective effect in winemaking is by adding [sulphur dioxide],” Specht said. “But you can add a non-Saccharomyces yeast selection such as the Level 2 Inita, and you’re able to achieve as good if not better antioxidant effects.

“There is interest in the wine industry in general in lowering the number of chemical inputs such as SO2. Something like this can really help and it will certainly improve the fruit quality of the wine.”

Another new Lallemand product is Go-Ferm Sterol Flash, a yeast rehydration protector for yeast preparation, to be used with cool water. Providing the same benefits to yeast as Lallemand’s Go-Ferm Protect Evolution, this new yeast protector doesn’t require warm water for preparation. It saves time, labour and water, which is especially important these days, and the yeast’s growth isn’t compromised.

“Before, winemakers would typically use warm water, add the yeast protector and, once it was in suspension, you could add the yeast. The overall process would take more than an hour,” Specht said. “But with Go-Ferm Sterol Flash, the entire process takes about 15 to 20 minutes. It’s a big time saver for winemakers and their cellar staff.” Feedback so far has been overwhelmingly positive since the product was launched in Canada in 2023. “Anything that saves time during crush is a big plus,” Specht said.

Also new in Canada, Stimula Pinot Noir, is a high-nitrogen yeast nutrient powder that is added at the start of fermentation to optimize a yeast’s ability to produce red and black fruit aromas, while simultaneously masking herbaceous and vegetal notes.

“It will help direct the style, but it will not make fruit from different areas taste the same,” Specht said. “If you are starting with fruit that is very light, a very finesse-oriented Pinot Noir, for instance, it will help you continue in that direction. It works with what you’re starting with.”

With a focus on innovation, the Lallemand Oenology team has plenty of new projects and products in the works, including inactivated yeast sprays to push phenolic maturity, so ripening is more consistent. “In general, we are looking at anything that can replace chemical inputs, whether it’s in the vineyard or in the cellar,” Specht said.

“Our basic philosophy is to find unique products to help winemakers. We are always looking toward the future.”